Same/different concept learning in the pigeon: the effect of negative instances and prior adaptation to transfer stimuli

Pigeons were trained on a matching-to-sample or oddity-from-sample task with shapes (circle and plus). Half of each group was exposed to “negative instance” trials i.e., for matching birds, neither comparison key matched the sample, and for oddity birds both comparison keys matched the sample. When all birds were transferred to a new task involving colors (red and green), nonshifted birds (transferred from matching to matching, or oddity to oddity) performed significantly better than shifted birds (transferred from matching to oddity, or oddity to matching), but only if they had experienced negative instances of the training concept. When all birds were exposed to negative instances of the transfer task and then transferred to a new color task (yellow and blue), dramatic transfer effects were observed. The effect of pre-exposure to the yellow and blue colors, in order to reduce transfer-stimulus novelty, had a minor effect on transfer.     

特征捆绑机制的理论模型

捆绑问题被认为是认知科学和神经科学的中心问题之一,对心理过程的认知神经机制研究起到了重要推动作用。特征捆绑机制研究有认知和神经科学两大范式。特征整合论在认知理论中最具代表性,形式理论修正了其在错觉性结合测量等方面的不足,双阶段理论突出了前注意捆绑。时间同步性理论是影响最大的捆绑理论,神经网络模型为捆绑机制提出了更具体的结构模型。两大范式的整合及由低级认知过程向高级心理过程的深化可能是今后捆绑机制研究的重点     

不同维度特征的共存对归类不确定性特征推理的影响

探讨在归类不确定的情境下,目标特征和预测特征的共存对特征推理的影响。共包括了三个实验,其中实验1、2考察了非靶类别中目标特征和预测特征的共存性对特征推理的影响,实验3考察了靶类别中目标特征和预测特征的共存性对特征推理的影响。三个实验五个分实验的结果一致支持了修正后的Bayesian规则,排除了“单类说”、“综合条件概率模型”的假设,并进一步修正了Bayesian规则为：     

归纳推理的抽样理论

作者提出归纳推理的抽样理论,认为归纳推理实质是根据与归纳特征有关的抽样样本情况来推断结论类别具有归纳特征的可能性,其中的抽样可分为类别抽样和特征抽样两种。以大学生为被试的两个实验结果一致支持抽样理论而不是别的归纳推理理论。对于归纳推理的主要现象,抽样理论比其它的相似性解释具有更大的解释范围,特别是能够解释其它理论严格不能解释的归纳推理非对称性现象     

ELECTROPHYSIOLOGICAL CORRELATES OF STIMULUS EQUIVALENCE PROCESSES

Research reported here concerns neural processes relating to stimulus equivalence class formation. In Experiment 1, two types of word pairs were presented successively to normally capable adults. In one type, the words had related usage in English (e.g., uncle, aunt). In the other, the two words were not typically related in their usage (e.g., wrist, corn). For pairs of both types, event‐related cortical potentials were recorded during and immediately after the presentation of the second word. The obtained waveforms differentiated these two types of pairs. For the unrelated pairs, the waveforms were significantly more negative about 400 ms after the second word was presented, thus replicating the “N400” phenomenon of the cognitive neuroscience literature. In addition, there was a strong positive‐tending wave form difference post‐stimulus presentation (peaked at about 500 ms) that also differentiated the unrelated from related stimulus pairs. In Experiment 2, the procedures were extended to study arbitrary stimulus—stimulus relations established via matching‐to‐sample training. Participants were experimentally näive adults. Sample stimuli (Set A) were trigrams, and comparison stimuli (Sets B, C, D, E, and F) were nonrepresentative forms. Behavioral tests evaluated potentially emergent equivalence relations (i.e., BD, DF, CE, etc.). All participants exhibited classes consistent with the arbitrary matching training. They were also exposed also to an event‐related potential procedure like that used in Experiment 1. Some received the ERP procedure before equivalence tests and some after. Only those participants who received ERP procedures after equivalence tests exhibited robust N400 differentiation initially. The positivity observed in Experiment 1 was absent for all participants. These results support speculations that equivalence tests may provide contextual support for the formation of equivalence classes including those that emerge gradually during testing.     

DYNAMICS OF CHOICE: RELATIVE RATE AND AMOUNT AFFECT LOCAL PREFERENCE AT THREE DIFFERENT TIME SCALES

To examine extended control over local choice, the present study investigated preference in transition as food‐rate ratio provided by two levers changed across seven components within daily sessions, and food‐amount ratio changed across phases. Phase 1 arranged a food‐amount ratio of 4:1 (i.e., the left lever delivered four pellets and the right lever one pellet); Phase 2 reversed the food‐amount ratio to 1:4, and in Phase 3 the food‐amount ratio was 3:2. At a relatively extended time scale, preference was described well by a linear relation between log response ratio and log rate ratio (the generalized matching law). A small amount of carryover occurred from one rate ratio to the next but disappeared after four food deliveries. Estimates of sensitivity to food‐amount ratio were around 1.0 and were independent of rate ratio. Analysis across food deliveries within rate‐ratio components showed that the effect of a small amount was diminished by the presence of a large amount—that is, when a larger amount was present in the situation (three or four pellets), the value of a small amount (one or two pellets) became paltry. More local analysis of visits to the levers between food deliveries showed that postfood visits following a large amount were disproportionately longer than following a small amount. Continuing food deliveries from the same source tended to make visits less dependent on relative amount, but a discontinuation (i.e., food from the other lever) reinstated dependence on relative amount. Analysis at a still smaller time scale revealed preference pulses following food deliveries that confirmed the tendency toward dependence on absolute amount with continuing deliveries, and toward dependence on relative amount following discontinuations. A mathematical model based on a linear‐operator equation accounts for many of the results. The larger and longer preference following a switch to a larger amount is consistent with the idea that local preference depends on relatively extended variables even on short time scales.     

捡了西瓜，就该丢掉芝麻吗——浅谈医源性Wernicke脑病

探讨医源性Wernicke脑病（WE）的病因、临床及磁共振图像特点,回顾性分析6例医源性WE病例。医源性WE病前均有禁食史,其临床表现多样。磁共振图像为中脑导水管周围T2WI及Flair高信号。大部分病例补充维生素B1后可好转。提示医源性禁食导致体内维生素B1耗竭是医源性WE的病因,及时补充维生素B1是预防及治疗本病的关键。     

整体加工方式下面孔结构与特征关系

探讨面孔整体性加工方式下结构信息和特征信息加工之间的关系。通过聚焦窗口技术在结构信息和特征信息的权变过程中考察二者对面孔整体性加工的影响, 从而进一步确定两类信息的加工关系模式。结果表明: 面孔以整体的方式进行加工; 结构信息加工系统和特征信息加工系统两者并行存在, 在当前实验任务中两类信息加工之间为竞争关系; 面孔以结构信息加工为主还是以特征信息加工为主取决于两类信息在当前任务中提取和加工难度。     

识别电位认知功能探析

识别电位(Recognition Potential, RP)是被试看到可识别视觉刺激时, 在200~250ms内达到峰值的脑电反应。识别电位的研究正处于理论探讨阶段, 有两种主要观点用于解释RP。一种观点强调RP反映了视知觉分析成分; 另一种观点强调RP反映了语义或概念加工成分。两种观点至今未达成一致。最近, 针对两种观点质疑, 研究者们提出了类别特征加工的观点, 这一新观点在理论上符合大脑经济性的原则, 具有一定的优越性, 但尚需要更多的实证研究的支持。未来的RP研究应从实验材料的多样化、多研究方法结合、类别特征加工能力的习得机制等方面展开。